Level 1 - Absolute Beginner
Seaborgium is a strange metal. It does not exist in nature. Scientists make it in a machine, a few atoms at a time.
The atoms do not last long. They break apart fast. So testing them is very hard.
Now a team has tested a seaborgium compound. It has seaborgium joined to six carbon monoxide molecules.
The team found that one bond is weaker than in tungsten, a lighter metal. The reason is a part of physics called relativity.
- metal
- A hard, shiny material like iron.
- atom
- A tiny piece of matter.
- machine
- A tool with parts that work together.
- compound
- A substance made of joined atoms.
- bond
- A link that holds atoms together.
- weaker
- Less strong.
- tungsten
- A hard metal used in light bulbs.
- relativity
- A part of physics about space, time and speed.
Level 2 - Elementary
Seaborgium is element 106 on the periodic table. It is named for the American chemist Glenn Seaborg. The element does not occur in nature. Scientists make it in particle accelerators, one atom at a time, and the atoms decay within seconds.
On Wednesday, the journal Nature published a study of a seaborgium compound. Each seaborgium atom is joined to six molecules of carbon monoxide, and the compound is written Sg(CO)6.
The team used a method called gas chromatography to learn how the compound behaves. They found that the first bond between seaborgium and a carbon monoxide molecule is weaker than the matching bond in tungsten hexacarbonyl, W(CO)6. Tungsten sits in the same column of the periodic table but is much lighter.
The authors say relativistic effects explain the difference. In very heavy atoms, the inner electrons move so fast that Einstein's relativity changes their energy. That changes how the atom bonds. Studies like this help chemists check whether the periodic table still works for the heaviest elements.
- element
- A basic substance made of one kind of atom.
- periodic table
- A chart that lists all known elements.
- accelerator
- A machine that speeds up tiny particles.
- decay
- To break down into other atoms.
- hexacarbonyl
- A compound with six carbon monoxide groups.
- chromatography
- A way to separate and study mixtures.
- electron
- A tiny particle that circles an atom's center.
- relativistic
- Related to Einstein's theory of relativity.
Level 3 - Intermediate
Seaborgium, element 106, is among the heaviest atoms chemists can study. It is named for Glenn Seaborg, does not occur naturally and is produced in particle accelerators one atom at a time, with isotopes that decay within seconds. Studying its chemistry is a feat of timing and patience.
A paper published in Nature on Wednesday reports gas chromatography of its hexacarbonyl, Sg(CO)6, a molecule in which a single seaborgium atom is surrounded by six carbon monoxide groups. The authors conclude that its first bond dissociation energy is lower than that of the lighter homologue, tungsten hexacarbonyl, W(CO)6.
The explanation lies in relativity. In very heavy atoms the innermost electrons move at an appreciable fraction of the speed of light, which alters the energies and sizes of the outer orbitals that do the bonding. The result is that seaborgium does not behave quite as its position below tungsten would predict.
That matters because the periodic table is a map built on patterns. If relativistic effects bend those patterns for the heaviest elements, the chart that organizes chemistry begins to fray at its edge, and experiments like this one show where.
- isotope
- A version of an element with a different number of neutrons.
- homologue
- A chemical that sits in the same group as another.
- bond dissociation energy
- The energy needed to break a chemical bond.
- orbital
- The region around a nucleus where an electron is likely to be.
- appreciable
- Large enough to be noticed.
- feat
- An impressive achievement.
- fray
- To start to come apart at the edges.
- alters
- Changes.
Level 4 - Advanced
At the bottom edge of the periodic table, chemistry is practiced on a handful of atoms that vanish within seconds. Seaborgium, element 106, named for Glenn Seaborg, is among them: synthesized in accelerators and studied before it decays. A paper in Nature on Wednesday reports gas chromatography of its hexacarbonyl, Sg(CO)6, and a finding that illuminates why the heaviest elements resist easy classification.
The authors report that the first bond dissociation energy of Sg(CO)6 is lower than that of tungsten hexacarbonyl, W(CO)6, the compound of its lighter congener in the same group. A naive extrapolation down the column would have predicted the reverse, or at least a similar value.
The discrepancy is attributed to relativistic effects. In atoms of such high nuclear charge, the inner electrons are whipped to an appreciable fraction of light speed, which contracts some orbitals and expands others and thereby rearranges the energies that govern bonding. Chemistry here is partly a corollary of Einstein.
The broader significance is epistemic as much as chemical. The periodic table has long been treated as a map of recurring behavior, and experiments on single atoms of superheavy elements are the only way to test whether the map holds at its frontier. This one suggests it bends, though not yet that it breaks.
- synthesized
- Made artificially through a controlled process.
- illuminates
- Makes clearer.
- congener
- A member of the same chemical group.
- extrapolation
- Extending a pattern beyond known data.
- discrepancy
- A difference between what is expected and what is found.
- corollary
- A natural consequence of something.
- epistemic
- Concerned with knowledge and how it is gained.
- superheavy
- Having a very high atomic number.
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